The present invention relates to a piston machine comprising a piston arranged in a cylinder in order to create a working chamber, and at least one pump chamber. The cylinder is provided with at least one suction port. A further injection port is arranged in the cylinder wall, connecting the pump chamber with a receiver.
The development of four-stroke automotive engines has been directed toward solutions that improve xe2x80x9cbreathingxe2x80x9d. As a result, even ordinary automobile engines contain 4 valves per cylinder. Recently systems of varying sophistication for controlling these engines, for example, as made in the VTEC-E engines from HONDA, have been developed.
Furthermore, the desire for higher power yield has resulted in the wide use of engines provided with turbo-supercharging.
Both trends in development have led to the use of more complicated and costly applications of components. This results in increased maintenance and repair costs.
However, the present invention is a simple solution that improves the normal air filling of four-stroke engines and makes supercharging possible on a regular scale.
Fundamentally, four-stroke engines can be supplied extra air by supplementing the amount of air sucked in through the traditional valve system with air supplied through ports. These ports are situated and made like the scavenging air ports in a two-stroke engine.
Because of the design of the ports, swirling in the combustion chamber can be influenced in a suitable manner and cooling of the piston tops, cylinder walls, and valves can be increased.
The air supply may be performed both at termination of each intake stroke and at the initiation of each exhaust stroke.
It is possible for the air supply to take place only at the termination of each intake stroke.
In the latter case, by using for example, a rotary valve rotating with an rpm 50% of the engine rpm, it is ensured that the air supply is only performed at the termination of the intake stroke.
Regardless of which solution is chosen, the timing for air supply must be relative to the ordinary valve system of the engine.
The indicated solutions may be realised in four-stroke engines, regardless of whether the piston drive forces are drawn by the use of traditional crank and connecting rod mechanisms, by the use of a new xe2x80x9cdouble connecting rod mechanismxe2x80x9d or by mechanisms that allow use of cylindrical piston rods reciprocated directly in the cylinder axis, as e.g. traditional crosshead engines, xe2x80x9ccrank loopxe2x80x9d engines by FICHT GmbH and Co. KG, xe2x80x9ctwisting piston enginesxe2x80x9d by Teisen, and engines with the xe2x80x9cI-yoke mechanismxe2x80x9d developed by me.
A machine of the type mentioned by way of introduction is known from U.S. Pat. Nos. 3,789,808 and 1,362,080. None of these machines would be able to work in connection with one-cylinder machines. Furthermore, they are connected with drawbacks because they require a high-energy consumption and exhaust a high degree of pollution.
Moreover, they are only constructed to work in connection with motors. Accordingly, they are not able to function as piston machines, in which the work chamber is a pressure chamber in a compressor, without auxiliary equipment.
It is the object of the present invention to provide a new piston machine in which the above drawbacks are obviated and where it is possible to obtain a surplus charging of the working chamber, thereby making it possible to increase the effect thereof.
According to the present invention this object is obtained with a piston machine being characterised in that the machine only has one piston in each cylinder. The piston by reciprocation sucks in a charge/charges of which at least one is a supplementary aftercharge to the charge/charges supplied at the suction valve, a scavenging port and/or by other supply system/systems. This may be a supplement hereto of the same or other kind, supplied to the working chamber of the combined working and pumping piston itself by being blown through at least one injection port formed in its cylinder wall only for this port being placed close to the position taken by the top of piston when the piston is in its bottom dead point and at least in a position that it becomes completely exposed by the piston top. One or more injection ports, by one annular duct, are mutually connected to at least one preferably short, exhaust duct connecting them with the dead volume in the pump which compresses the supplementary aftercharge, which dead volume has been minimised. A differential pressure controlled check valve is disposed in exhaust duct close to the dead volume of the pump. A receiver is connected with the exhaust duct. The receivers used in the machine are designed so that their individual volumes may be increased or reduced by manual adjustment.
Due to the specific arrangement of the injection port in the cylinder wall a specific benefit is obtained. Thus there is achieved a piston controlled opening and closing of the injection port/ports. This determines the opening period, which is the basis for the period of injection, determined by the reciprocation speed of the piston during its passage of the injection port/ports, which injection period in connection with the charging pressure and the flow resistance arising from the feeding of the charge determines the extent of the aftercharge supplied to the working chamber in the injection period. The latter, therefore, being the cause of the preferred use of several injection ports.
In order to minimise the dead volume it is possible to establish the least possible clearance between the pump piston and the bottom part of the pump cylinder. This immediately causes an unsuitably high pressure on the charge in the pump. The charge is sucked in through a suitably short injection duct and is retained in the pump. The correct suction through the injection duct and retention of the charge in the pump is ensured by the use of the differential pressure controlled check valve.
The specific arrangement of the receiver, which has a dead volume, makes it possible to increase the dead volume of the pump and the volume of the duct connections extended to the injection ports. Moreover, the charge is compressed to the pressure that is most suitable for the application of the machine at the rpm and load preferred in use. This makes the machine advantageous for functioning in a range only slightly deviating from the rpm and the load at which it is intended to operate with the associated receiver. However, replacement is needed to adapt to another rpm and load range without an unsuitable increase of loss caused by throttling at the intake and loss by compression and injection occurring.
If the engine is subjected to varying rpm""s and loads, as in an automotive engine, the machine is suitable for in the indicated design. It can perform aftercharging even from low rpm because it automatically adjusts to the load requirements it is subjected to. For example, it adjusts to variations such as speeding up or down, gearing up or down, or by external conditions, such as road inclinations, or head and tail wind, and if desired, it can compensate for centrifugal forces arising from road bends and other sudden steering turns. Furthermore, it is especially suitable for the purpose because the performed automatic regulating operations keep the mixing ratio of fuel and air supply suitable for immediate operating situations. This contributes to a r more even driving. Both conditions are important for achieving fuel savings and reducing exhaust pollution.
A piston machine has a charge collected and stored while the piston, by its reciprocating from its top dead point, toward its bottom dead point performs suction of the succeeding charge. The piston at the top of its stroke, initiates the exposing of the injection ports formed in the working cylinder, commencing injection of the charge previously compressed in the pump. Immediately after the check valve, the suction duct and the receiver determine the magnitude of the charge pressure that is associated with the dead volume of the pump. A likewise pressure differential controlled check valve is inserted in the inlet opening of the exhaust duct, immediately before a receiver associated with this duct. The receiver may be a combined receiver and pressure regulator retaining the compressed charge in the receiver until the exposure of the injection port/ports by the piston is injected to the working cylinder of the piston, which is a design, though requiring two check valves. This allows the piston to have a greater skirt diameter. In addition, because of the outward collaring of the piston, there is an increased lower diameter, making possible the use of a shorter connecting rod with greater freedom of deflection. As its form dictates, the annular pumping chamber is isolated from receiving lubrication. This is disadvantageous because an ordinary crank and connecting rod mechanism generates important lateral pressure on the piston. Also, increased piston weight makes the machine less suitable for applications with varying rpm.
The piston machine makes use of two different types of yoke mechanisms. Both mentioned mechanisms are advantageous because they ensure exact piston reciprocation in the cylinder axis. Performing sinusoidal (harmonic) piston strokes by evenly performed rotations is a simple way to make possible a complete (100%) outbalancing of all reciprocating masses in the cylinder axis. For the number of cylinders commonly used, also a complete (100%) outbalancing of the masses moved perpendicularly to the cylinder axis without the use of balancing mechanisms is desired. The xe2x80x9cScottish yoke mechanismxe2x80x9d reduces the lateral pressure on the piston rod and the piston to 50% of that generated by a crank and connecting rod mechanism used for the same purpose. While the xe2x80x9cI-yoke mechanismxe2x80x9d operates without any generation of lateral pressure on the piston rod and the piston, the piston is isolated from the crank disc chamber and is not supplied with lubricating agent here from in a suitable manner. There is a need for relief of lateral pressure. This is because it both acts as a piston in the working and pump chamber under thermal load conditions. The working conditions are counteracted in the machine either by: adding a lubricating agent to the charge sucked into the charging pump by fog lubrication to the least practicable extent and which later, by combustion or by its presence in a compressed gas, is the least possible contaminating, or by quite simply using the elimination of the lateral pressure on the piston for completely avoiding lubrication, advantageously reducing the exhaust contamination, either by coating the piston rings, alternatively the piston and/or the cylinder with a film. For example, an amorphous diamond film developed by Sandia Laboratories, which can be coated at room temperature, is temperature resistant until 800 degrees Celsius, stress-free, safe against cracks, possesses a hardness corresponding to 90% of that of crystalline diamond, is resistant against most chemicals, and has a very low coefficient of friction. By using light, temperature resistant materials for the piston rings, the piston and/or the cylinder, may be provided with smooth surfaces, for example, ceramic type surfaces. The design and materials interact with automatically controlled, combined receivers and pressure regulators to make the machine capable of advantageous design in relation to its developed torque and yield, being used as a light and compact automotive four-stroke engine. Alternatively, it can be used as a single-stage compressor, made like a xe2x80x9cboxerxe2x80x9d engine with two piston sets per yoke disposed in the same cylinder axis, projecting to both sides of the common yoke. Furthermore, the supplementary aftercharge eliminates or limits the need more complicated and voluminous top valve constructions with increased numbers of valves per cylinder.
The charge in engines with direct fuel injection is atmospheric air. If necessary for lubrication of the isolated piston part, the atmospheric air may be supplied with a small oil fog content. In engines with indirect fuel supplies, a small oil fog content can be established by a fuel injection system associated with the supply duct of the aftercharge pump or a carburettor allowing the charge to be a suitable mixture of air, fuel and oil.